1. Field of the Invention
The present invention relates to a hydrogen-used internal combustion engine.
2. Background Art
As disclosed in, for example, Japanese Patent Laid-open No. 2003-343360, internal combustion engine systems provided with hydrogen generation capability are known in the art. Specifically, such a system comprises a mechanism to generate a hydrogen rich gas and dehydrogenation product such as naphthalene from a hydrogenated fuel containing organic hydrides such as Decalin as well as a hydrogen engine which runs on the generated hydrogen rich gas as fuel.
In the system disclosed in the above-mentioned publication, while a hydrogen engine is operating, hydrogenated fuel is separated into a hydrogen rich gas and dehydrogenation product by utilizing the heat generated by the operation. In more detail, hydrogen is obtained by injecting the hydrogenated fuel onto a catalyst to cause dehydrogenation reaction on the catalyst.
[Patent Document 1] Japanese Patent Laid-open No. 2003-343360
[Patent Document 2] Japanese Patent Laid-open No. 2002-255503
[Patent Document 3] Japanese Patent Laid-open No. 7-63128
In the systems disclosed in the above-cited publications, the dehydrogenation product is collected after stored for a time. Alternatively, however, it may also be possible to construct a system where the dehydrogenation product is supplied as fuel (dehydrogenated fuel) to the engine. In this case, hydrogen and dehydrogenated fuel are supplied to the internal combustion engine at such a ratio as to secure both engine efficiency and emission performance.
On the other hand, hydrogen and dehydrogenated fuel are separated from the hydrogenated fuel at a fixed ratio. If an amount of hydrogen required by the internal combustion engine is separated from the hydrogenated fuel, the amount of dehydrogenated fuel generated together with hydrogen exceeds the amount of dehydrogenated fuel required by the internal combustion engine. Thus, excessive dehydrogenated fuel occurs whenever hydrogen is separated as required.